Actually they are starting to be fairly popular with the more well known mills. Loro Piana and Zegna have these as well. I am actually lookingat the zegna one and its called silk linen (51% silk 49% linen). Fairly nice fabric actually. Nice sheen and slubby.
I think you don,t see alot of silk blends mentioned on SF because folks here don't like even the smallest amount of sheen what-so-ever.
I have a lovely silk-wool blend jacket for summer, as well as a slightly more 'fashion-foward' wool-lycra blend blazer (which still looks like a traditional boat club blazer, but it stretches...). I have no problem with a subtle sheen on materials that are supposed to have that quality (silk and mohair in particular), and I think the only reason why some people dislike it is because they associate it with shiny cheap modern polyster or poly-wool blend suits.